how to find the largest sequence in the given string.Can u find where i have gone wrong in the below code?

Question

#include<stdio.h>

#include<string.h>

int main ()

{

  char str[100], sub[50], *p, temp[50];

  int i, len;

  setbuf (stdout, NULL);

  printf ("Give a Sequence:");

  gets (str);

  printf ("The Sequence u want:");

  gets (sub);

  len = strlen (sub);

  do

    {

      p = strstr (str, sub);

      if (p == '\0')

{

    len--;

  strncpy (temp,sub,len);

  strcpy (sub, temp);

}

    }

  while (p == '\0');

  printf ("The biggest sequence is:");

  puts (sub);

}

sample output:

Give a Sequence:dftfhglhjuhjh

The Sequence u want:hjhhh

The biggest sequence is:hjh

Answer 1

I have corrected the code:

#include<stdio.h>
#include<string.h>

int main ()
{
  char str[100], sub[50], *p;
  int i, len;
  setbuf(stdout, NULL);
  printf("Give a Sequence:");
  gets(str);
  printf("The Sequence u want:");
  gets(sub);
  len = strlen(sub);
  printf("len=%d",len);
  do
  {
      p = strstr (str, sub);
      if (p==0)
      {
          char temp[50]={0};     // declare and initialze in loop
          printf("sub=%s\n",sub);
          strncpy (temp,sub,--len);
          strcpy (sub, temp);
      }      
  }while(p==0);
  printf ("The biggest sequence is:");
  printf("%s",sub);
}

The temp[50] you are using must be cleared every time the loop runs and use p==0 instead of p=='\0' as it causes segmentation fault